Updated catalogue of Iran’s endemic angiosperms

This study aims to provide a thorough and updated checklist of endemic angiosperm species in Iran, outlining patterns of diversity and identifying priorities for their conservation. Accurately identifying and regularly updating the status of a country’s endemic species plays a fundamental role in understanding its biological richness and is significant from multiple perspectives: it contributes to the documentation and preservation of unique biodiversity assets, facilitates the analysis of biogeographic patterns, supports informed and targeted conservation planning, tracks taxonomic and nomenclatural changes, and serves as an essential tool for monitoring the ecological consequences of climate change, habitat degradation, and land-use transformations. Repeating and periodically updating this work may reveal notable trends and provide valuable insights into the dynamics of plant endemism and biodiversity change over time. In addition, establishing an open-access, regularly updated online checklist of Iranian endemic plants would be highly notable not only as an educational and scientific resource, but also as a practical tool for researchers, conservationists, and educators alike. Moreover, recent publications have emphasized the importance and utility of endemic plant checklists. For instance, Villaseñor (2016) presented an updated inventory of Mexico’s native vascular plants, highlighting that a substantial proportion are endemic to the country. Similarly, Mir et al. (2019) compiled a comprehensive checklist of endemic flora in Meghalaya, India, emphasizing the significance of such resources for conservation and biodiversity studies. Additionally, El Zein et al. (2025) compiled a checklist of endemic plants in Lebanon. Such updated national checklists not only provide essential insights into biogeographic affinities but also serve as indispensable tools for prioritizing conservation strategies, as exemplified by the Lebanese checklist (El Zein et al., 2025). Although several checklists of Iranian endemic plants have been published thus far (e.g., Ghahreman & Attar, 1999; Jalili & Jamzad, 1999; Emami & Aghazari, 2011; Noroozi et al., 2019a), the accelerating pace of botanical research in recent years, particularly the increasing use of molecular tools, means that while they remain valuable, more recent studies have continued to refine and expand our knowledge. For the grass family (Poaceae), a comprehensive and valuable checklist has been provided separately, which constitutes an important reference for floristic and taxonomic studies in Iran (Bidarlord & Ghahremaninejad, 2022). Shifts in taxonomic concepts and phylogenetic understanding have prompted the authors of the present study to compile a revised and up-to-date catalogue. For instance, Zhumeria majdae Rech.f. & Wendelbo, which appeared in the previous lists, is now recognized as Salvia majdae (Rech.f. & Wendelbo) Sytsma, based on robust molecular phylogenetic evidence (Drew et al., 2017). Numerous similar reclassifications have emerged in recent years. Another example is the monotypic genus Hypericopsis Boiss., formerly considered a valid and endemic genus in Iran. Molecular data provided by Gaskin et al. (2004) demonstrated that it belongs within Frankenia L., thereby rendering Hypericopsis a taxonomic synonym. Although Frankenia persica (Boiss.) Jaub. & Spach [= Hypericopsis persica Boiss.] remains a species endemic to Iran, Hypericopsis is no longer accepted as a distinct and endemic genus, but still appearing in some botanical works. Similarly, two endemic species formerly placed in Ferulago have recently been transferred to two other genera, namely Anisotaenia and Lophosciadium, according to the most recent treatment (Lyskov et al., 2025). Additionally, several taxa previously considered endemic have since been discovered in adjacent regions and are no longer classified as such. In preparing this checklist, the authors have limited the scope to species-level taxa, deliberately excluding endemic subspecies and varieties. This decision was made to promote consistency in defining endemism and enable more straightforward comparisons across studies. It is also worth noting that since the publication of the most recent comprehensive checklist in 2019, approximately 200 new endemic plant species have been described from Iran, underscoring the urgency of periodic reassessment. Overall, while the present work does not seek to propose new taxonomic or biogeographic frameworks, it aims to provide a consolidated and updated foundation for future studies in systematics, floristics, and conservation planning. In this context, one of the major limitations of updated endemic checklists, including the present study, is the inherent uncertainty regarding the possible extinction of older recorded species or the status of newly described taxa whose type specimens have been stored in herbaria for many years but may no longer exist in the wild. This means that the checklist we provide may include species that are possibly extinct or no longer extant in their natural habitats, reflecting an unavoidable discrepancy between documented biodiversity and current reality. Such limitations emphasize the essential need for continuous field surveys, population monitoring, and periodic verification to update and refine endemic species lists accurately. Endemism, the restriction of species to a specific area, is central to biodiversity and conservation. Endemism, the ecological state of being unique to a defined geographic location, is a fundamental concept in biogeography, biodiversity science, and conservation planning. Endemic plant species often arise through long-term geographical, climatic, and ecological isolation and are invaluable for understanding evolutionary processes. Due to their narrow distributions and habitat specificity, endemic plants are particularly vulnerable to environmental changes, making them key targets for conservation (Kruckeberg & Rabinowitz, 1985; Myers et al., 2000). As climate change intensifies, endemic species especially those with limited physiological plasticity or dispersal capabilities are at heightened risk of decline or extinction (Enquist et al., 2019; Wiens & Graham, 2005). Mountainous and arid regions, where microclimatic niches and elevational refugia are prevalent, face especially acute threats, as many endemic species may not be able to migrate or adapt fast enough to shifting climate zones.

Endemism and plant diversity in Iran

The endemic species of Iran have been introduced to the scientific world over a period of 225 years, from 1800 to the present (2025). Iran represents one of the most significant centers of continental plant endemism globally. This complex positioning, combined with high geological, climatic, and topographic diversity, has fostered the emergence of numerous endemic taxa. The country is dominated by several major mountain ranges, including the Alborz, Zagros, and various central Iranian massifs such as Karkas and Shirkuh. These “sky islands” create a mosaic of microclimates and ecological barriers, promoting allopatric speciation similar to patterns seen in island ecosystems and mountainous biodiversity hotspots (Steinbauer et al., 2016). As a result, Iran’s endemic plants are especially concentrated in montane and high-altitude habitats (Jowkar et al., 2016). The genus Astragalus (Fabaceae) is the most diverse and endemism-rich, with over 850 species, many of which are local or narrow-range endemics (Maassoumi, 2020; Ghahremaninejad et al., 2025). Other endemic-rich genera include Acanthophyllum, Cousinia, and Euphorbia. In general, some endemic species have a relatively wide distribution range within the country, for instance, Colutea persica Boiss. (Pooyan et al., 2014). However, there are also cases where they form very small populations. For example, Astragalus fridae Rech.f. (Podlech & Zarre, 2013) grows exclusively on gypsum soils within a very limited area in Semnan Province. Another example is the narrow endemic Astragalus ferdowsi-toosii (Ghahremaninejad et al., 2025), which occurs in Khorassan Province and grows on soils with high levels of arsenic and sulfur. Many of these narrow endemics are struggling to reproduce in their natural habitats and are highly vulnerable to sudden environmental changes. They clearly require protection, which first and foremost depends on having a comprehensive list of such plants, the primary aim of this article. The exceptional genetic diversity observed in several genera in Iran highlights the country’s importance in taxonomy and conservation biology. These genera-specific centers of diversity reflect a broader trend: Iran is a vital reservoir of plant endemism in the Irano-Turanian region and globally significant for the study and preservation of evolutionary processes. In Iran, the average rate of new species descriptions since the beginning of the 21st century is approximately 38 species per year.

Materials and Methods

To assess endemic diversity, we compiled an updated, comprehensive checklist of Iran’s endemic angiosperms flora by integrating data from multiple authoritative sources. Primary inputs were drawn from floras covering Iran, such as Flora of Iran (Assadi, 1989-2024) and Flora Iranica (Rechinger, 1963-2015), as well as comprehensive online databases including Plants of the World Online (POWO, 2025), the International Plant Names Index (IPNI, 2025), and the Global Biodiversity Information Facility (GBIF, 2025). The compilation followed a stepwise protocol: (1) extraction of species names from floristic treatments and recent taxonomic literature pertaining to Iran; (2) verification of taxonomic and nomenclatural status (accepted names, synonyms, basionyms) via POWO and IPNI; and (3) identification of endemism based on documented geographic distributions, primarily using GBIF records and corroborating evidence in the aforementioned sources. Endemic species were defined as those native to, and restricted exclusively within, the political boundaries of Iran. The checklist was limited to species-level taxa; endemic subspecies, varieties, and forms were deliberately excluded. This was done to keep the checklist simple, consistent, and directly comparable, without complications from infraspecific categories. Given ongoing taxonomic revisions, re-circumscriptions, synonymizations, and the description of new taxa, endemism assessments are inherently dynamic. Some taxa currently treated as endemic may eventually be recorded from neighboring countries, whereas others may be split into multiple local endemics as new evidence emerges (Humphreys et al., 2019). This checklist builds upon the foundational data provided by floras covering Iran, complemented by numerous taxonomic publications indexed in international databases. The accepted names were standardized and confirmed primarily through POWO and IPNI, and, in some cases, GBIF. The circumscription of families and orders in this study follows the APG IV (2016) classification system. All numerical calculations and graphical representations in this study were carried out using the data provided in Table 1. This table contains the primary values employed and served as the basis for the analyses and quantitative results.

Results

Our updated checklist comprises 2,503 endemic angiosperm species in Iran, spanning 58 families and 26 orders. The ten orders with the highest numbers of endemic species are Fabales (715; 28.56%), Asterales (526; 21.01%), Lamiales (234; 9.34%), Caryophyllales (232; 9.26%), Asparagales (134; 5.35%), Apiales (112; 4.47%), Boraginales (94; 3.75%), Rosales (81; 3.23%), Brassicales (76; 3.03%), and Ericales (49; 1.95%). Together, these orders constitute the majority of Iran’s endemic flora, whereas each of Acorales, Alismatales and Arecales is represented by only a single endemic species (Figure 1). Considering the number of endemic species reported for Iran in this paper (2,503 species), and based on the most recent figure for the angiosperms of Iran (8,090 species; Ghahremaninejad et al., 2017), it can be concluded that about 31% of the Iranian angiosperm flora, i.e. slightly less than one-third, are endemic to the country. In comparison with Iran’s neighboring countries, Turkey can be mentioned, where out of about 12,000 vascular plant taxa, nearly 32% have been reported as endemic (Güner et al., 2012; Noroozi et al., 2019b). At the family level, the Fabaceae is by far the most diverse and endemism-rich family, 712 species (28.44%), followed by Asteraceae (511; 20.41%) and Lamiaceae (143; 5.71%). Other prominently represented families include Caryophyllaceae (121; 4.83%), Apiaceae (112; 4.47%), Boraginaceae (94; 3.75%), Rosaceae (78; 3.11%), Brassicaceae (73; 2.91%), Amaryllidaceae (69; 2.75%), and Plumbaginaceae (55; 2.19%). Together, these families account for nearly four-fifths (78.57%) of all endemic species in Iran, with the remaining 48 families collectively comprising 21.43% (Figure 2). At the genus level, Astragalus alone harbors 592 endemic species, highlighting its extraordinary diversification in Iran, followed by Cousinia, Allium, and Acantholimon.

Figure 1. Endemic species richness of orders in Iran's flora.

Figure 2. Families and the number of their endemic species in the flora of Iran.

In total, Iran’s endemic plants belong to 333 genera, with Astragalus being the most species-rich genus at 592 species (23.65%). Other prominent genera include Cousinia with 212 species (8.46%), Allium with 67 species (2.67%), Acantholimon with 54 species (2.15%), Echinops with 48 species (1.91%), and Dionysia with 47 species (1.87%). The list continues with Onosma at 46 species (1.83%), Centaurea and Nepeta with 45 species each (1.79%), and Onobrychis with 43 species (1.71%). Together, these ten most species-rich genera account for 47.63% of all endemic species (Figure 3).

Figure 3. Genera with the most endemic species in Iran's flora

The first endemic plant species of Iran, Nepeta crispa Willd., was introduced to the scientific community in 1800. The years with the highest number of endemic species introductions, in descending order, are: 1846, 2003, and 2005, each with 82 species; 2013 with 63 species; 2006 with 59 species; 1988, 2017, and 2023, each with 52 species; and 2014, 2015, and 2018, each with 51 species. Considering 25-year intervals for the years of new endemic species records in Iran, some interesting trends emerge. From 1800 to 1825, 10 species (0.39%) were recorded; from 1826 to 1850, 236 species (9.42%); from 1851 to 1875, 196 species (7.83%); from 1876 to 1900, 74 species (2.95%); from 1901 to 1925, 100 species (3.99%); from 1926 to 1950, 136 species (5.43%); from 1951 to 1975, 197 species (7.87%); and from 1976 to 2000, 464 species (18.53%). A marked rise is observed in the 2001–2025 period, with 1,090 species (43.54%) recorded (Figure 4).

Figure 4. Historical trend of species descriptions from Iran (1800–2025), showing changes in taxonomic activities over time.

Discussion

The observed patterns of endemism in Iran reflect a combination of historical, climatic, and topographical factors. The country’s position at the convergence of three major phytogeographic regions (Irano-Turanian, Saharo-Sindian, and Euro-Siberian), together with its complex mountain systems and varied microclimates, has promoted speciation and endemism. The remarkably high number of endemic species in Astragalus and Cousinia underscores the role of habitat specialization and rapid diversification in shaping Iran’s flora. Nevertheless, data gaps and taxonomic inconsistencies continue to limit a full understanding of the country’s endemic diversity. The present checklist provides a critical baseline for future phylogenetic, biogeographic, and conservation research. Endemic plants, with their limited geographic ranges and specialized habitat requirements, are particularly vulnerable to environmental changes, habitat fragmentation, and land-use alterations. In the context of rapidly accelerating climate change, effective conservation strategies must integrate multiple approaches, including in situ protection of refugial and high-altitude habitats, ex situ conservation through seed banks and botanical gardens, and maintaining ecological connectivity to facilitate altitudinal and latitudinal migrations (Hannah et al., 2007). Although some endemic species exhibit adaptive potential via phenotypic plasticity, genetic diversity, or dispersal capabilities, these traits are often limited in taxa confined to narrow ecological niches (Jump & Peñuelas, 2005). Therefore, prioritizing the protection of endemic-rich regions in Iran, particularly montane and steppe ecosystems, is essential for safeguarding the country’s unique biodiversity in the long term.

Conclusion and Recommendations

It is hoped that this updated checklist provides the most comprehensive and current synthesis of Iran’s endemic angiosperms to date. It reaffirms the country’s remarkable floristic richness and highlights geographic regions and taxonomic groups that require urgent conservation attention. To ensure continued relevance, it is recommended that a dynamic, publicly accessible digital platform be established to enable timely updates and effective data integration. Building on our findings, the following priority actions are proposed to guide research and conservation efforts: (1) establish and maintain a national online database for Iranian endemic plants to facilitate continuous updates and data sharing; (2) strengthen conservation programs focused on threatened endemic hotspots; (3) promote multidisciplinary research, including molecular phylogenetics, ecological niche modeling, and biogeographic analysis, to elucidate the evolutionary origins and adaptive capacities of endemic taxa; (4) enhance public awareness and foster community engagement by highlighting the ecological and cultural importance of Iran’s endemic plants; and (5) assess the potential impacts of climate change on the distribution, viability, and migration of endemic species. It is also emphasized that collaborative efforts are important in establishing a comprehensive and user-friendly database of Iran’s endemic plants. Such a platform, with continuous data updates and support for interdisciplinary research, would serve as an effective tool for monitoring floristic change and informing conservation policies. It is believed that the achievement of this goal will not be possible without the collaboration of botanists and conservation specialists.

Acknowledgements

The authors gratefully acknowledge all botanists and plant collectors, past and present, whose years of fieldwork, taxonomic expertise, and floristic research have laid the foundation for this checklist. We are also grateful to the esteemed reviewers and the editor, whose insightful comments and constructive suggestions greatly enhanced the quality of this article.